As you get started on building your new fireplace, AW Perkins Castable Refractory Cement is the perfect mortar choice and can be used between bricks as well as for resurfacing, coating, and setting. The case includes 24 half-pound tubs that can be used in masonry-to-masonry joints that are less than 1/4 inch thick and will be a beautiful buff color when cured. This ready mixed cement makes an ideal mortar to use between the fire bricks of your fireplace firebox. After it has been heat cured, this mortar can withstand temperatures up to 2000 degrees F.